THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIEiSrCE. 



CONDUCTED BY 



SIR DAVID BREWSTER, K.H. LL.D. F.R.S.L. & E. &c. 

 RICHARD TAYLOR, F.L.S. G.S. Astr. S. Nat. H. Mosc.&c. 

 SIR ROBERT KANE, M.D., F.R.S., M.R.I.A. 

 WILLIAM FRANCIS, Ph.D. F.L.S. F.R.A.S. F.C.S. 

 JOHN TYNDALL, F.R.S. &c. 



" Nee aranearum sane textus ideo melior quia ex se fila giguunt, uec noster 

 vilior quia ex alienis libamus ut apes." Just. Lips. Polit. lib. i. cap. 1 . Not. 



VOL. XIII.— FOURTH SERIES. 

 JANUARY— JUNE, 1857. 



L O ND O N. 



TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 

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SOLD BY r.ONGMAN, BROWN, GaiiEN, LONGMANS, AND ROBERTS; SIMPKTN, 

 MARSHALL AND CO. J WHITTAKEU AND CO.; AND PIPEK AND CO., 



LONDON : BY ADAM AND CHARLES BLACK, AND THOMAS 



CLARK, EDINBURGH; SMITH AND SON, GLASGOW ; 



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